Total Lunar Eclipse -
What You Need To Know

On the evening of January 20, 2019, observers across the United States will
get to view a total lunar eclipse, weather permitting!

What is it?

A lunar eclipse happens when the moon's orbit takes it into the shadow
of the Earth. This means it only happens at the time of the full moon. This is
opposed to a solar eclipse where the Earth wanders into the shadow of the
moon and happens at the time of the new moon.

Is it safe to view?

Viewing a lunar eclipse (partial or total) is entirely safe! A solar
eclipse, on the other hand, is notoriously unsafe and special precautions
need to be observed. This is why you need to know the difference between a
Lunar and Solar eclipse.

Eclipse Diagram

At the right is a Lunar Eclipse Diagram. There are actually two parts of
the Earth's shadow: the inner dark shadow, the umbra, and the lighter outer
one, called the penumbra. Umbra is Latin meaning shade or shadow. The "Pen"
in Penumbra is from the Latin paene which means almost.

One of the best aspects of any lunar eclipse is if there's one going on and
the moon is above the horizon, you'll be able to see the eclipse!

Phases of a total lunar eclipse as photographed by Paul
Borchardt during the one that occurred on September, 2015. The
middle picture is the total phase, whereas the outer 4 are the
partial phase.

There are actually 3 kinds of lunar eclipses: penumbral, partial, and
total.

A penumbral eclipse occurs when the moon wanders into the penumbra. If you
were on the moon looking toward the sun, you'd see a partial solar eclipse.
So the moon is still being fairly illuminated so from Earth we see a very
slight dimming. But the dimming is so little it is hardly noticeable.

A partial eclipse occurs when the moon wanders into the umbra, the dark
shadow cast by the Earth. As seen here on Earth, you can see that curved
dark shadow moving over the face of the moon. (The 4 outer photos.) The
curve, of course, is the disk of our planet. (This curved shadow was a clear
sign by the Greeks that the Earth was a sphere. It also allowed them to make
a good approximation of the distance to the moon.) Whenever there is partial
eclipse, it will be proceeded and followed by a penumbral one.

A
total eclipse occurs when the entire moon wanders into the umbra. Though it
would seem looking at the partial phases that a total eclipse would mean the
moon would be entirely dark and hence, not very interesting, but as
viewed from the moon there is still light coming from light bending from the Earth's atmosphere -
basically the colors of our sunsets so the moon actually looks orange to red
in color. This is why the total lunar eclipse is often called the "blood"
moon.

When there is total eclipse, there will also be partial eclipse proceeding
and following.

What You Need to See the Eclipse

You need nothing more than your own eyes! As stated earlier, viewing a lunar
eclipse is entirely safe so no eye protection is needed (unlike a solar eclipse
where you must take extreme precautions.) Of course you need to be able to see
the moon. That means clear enough weather and an unobstructed view. You don't
need to see much of the sky, just as long as the moon is in view. It goes
without saying that because this eclipse is happening in January, you will
probably have to dress warm, unless you are lucky enough to see it through a
window.

Though you can see this event with your eyes, if you have binoculars
we highly recommend having them to augment the view. And if you have a
telescope, better still!

Total Lunar Eclipse - September 27, 2015

World View Eclipse Diagram

This diagram shows the visibility of the January 20-21 eclipse. The
middle white area is where the entire eclipse is visible. The dark gray
area is where no part of the eclipse will be seen because the moon will
be entirely below the horizon. The other areas indicate areas where only
some of the eclipse will occur when the moon is visible.